In malt alcohol beverages (such as beer and low-malt beer (Happoshu)) that use malt as a raw material, a variety of reactions, including oxidation and dehydration of their components, are promoted during or after their production by virtue of the lapse of time or the increase in temperature (generally referred to as “the stale flavor of malt alcohol beverages”). Consequently, it is known that the original flavor of malt alcohol beverages is impaired.
Therefore, different measures are taken in order to prevent the qualities of such malt alcohol beverages from being deteriorated. Specifically, among others the quality control after production, the time management after production to sale, the temperature control during transportation are strictly enforced, which allows products with freshness and high quality to be provided. However, even if the aforementioned management is thoroughly employed, it has been difficult to stably maintain the freshness obtained immediately after production for a prolonged period of time.
A method of suppressing the oxidation of a malt alcohol beverage during its production to stably maintain the freshness immediately after production was developed that relays on decreasing the oxygen concentration of the atmosphere in the entire process or a part thereof during the production of the malt alcohol beverage (Japanese Patent Application Laid-Open Gazette No. 2000-4866). According to this method, by decreasing the oxygen concentration of the atmosphere during production, the reducing power of intermediate products in the production process is enhanced with the result of increased reducing power of the final product, which has made it possible to enhance resistance to the oxidation or aging of the malt alcohol beverage.
However, while the method of producing a malt alcohol beverage described in Japanese Patent Application Laid-Open Gazette No. 2000-4866 can prevent the malt alcohol beverage from being oxidized to certain degree, it is not necessarily adequate to suppress the aging of the flavor after production for a prolonged period of time.